In my U.S. Pat. No. 3,905,623, a pipe coupling is disclosed in which a wide-band sleeve is stretched over adjoining pipe ends to provide a mechanical connection with a fluid seal between the pipes. That patent disclosed a coupling for a pipe lap joint in which the end of at least one of the pipes is specially formed to provide the desired relationship with means for clamping or stretching the outer pipe around the inner pipe. In this coupling, the coupling includes a sleeve having a roundish sector and a channel-shaped sector and force applying means connected with the channel-shaped sector is adapted to stretch the sleeve to form the joint.
A coupling for pipe lap joints is disclosed in my U.S. Pat. No. 4,056,273 which allows two pipes to be joined in telescoping relation without requiring the pipe ends to be specially formed. In this coupling, a wide-band sleeve has a cross section including a roundish sector and a radially projecting channel-shaped sector and is adapted to receive a pipe of one diameter inside one end and a pipe of a larger diameter inside the other end with the pipes being in telescoping relation to form a lap joint. The roundish sector of the sleeve is substantially uniform in diameter throughout its length and hence is oversized with respect to the smaller pipe. A split seal ring encircles the smaller pipe and has an outer diameter about the same as that of the larger pipe. Force applying means is connected with the channel-shaped sector to stretch the sleeve around the pipes. By reason of the split seal ring, the sleeve is stretched circumferentially in a substantially uniform amount along its length into engagement with the outer pipe and the seal ring, respectively, to produce a mechanically strong and fluid tight seal.
It is a general object of this invention to provide a coupling for pipe lap joints having the advantages of a stretched wide-band sleeve, as in the above mentioned patents, but without the need for either specially formed pipe ends or a seal ring for the smaller pipe.